Belt-grinding machine



May 3, 1960 s. KARBOWSKI BELT-GRINDING MACHINE 4 Sheets-Sheet 1 FiledDec. 23, 1958 INVENTOR Ha rbowsfi i Sylvester May 3, 1960 s. KARBOWSKIBELT-GRINDING MACHINE Filed Dec. 25, 1958 4 Sheets-Sheet 2 INVENTORSq/vester Karbows/{i 480M r @cvrfiomw ATTORNEYS May 3, .1960 s.KARBOWSKI 2,934,864

BELT-GRINDING museum 4 Sheets-Sheet 3 Filed Dec. 23, 1958 INVENTORSylvester Harbocus/ii ATTORNEYS S. KARBOWSKI BELT-GRINDING MACHINE May3, 1960 Filed Dec. 23, 1958 4 Sheets-Shag: 4

1 N VENTOR Ha rbowshi ATTORNEYS BELT-GRINDING MACHINE SylvesterKarbowski, New Haven, Conn., assignor to Progressive Tool &Manufacturing Company, East Haven, Conn., a partnership ApplicationDecember 23, 1958, Serial No. 782,501

9 Claims. (Cl. 51-141) One object of the invention is to provide animproved grinding machine of this type.

Another object is to provide a beltgrinding machine having greatflexibility of operation.

Another object is to provide, in such a machine, an angularly adjustablegrinding head and improved means for gauging the degree of adjustment ofthe head.

Still another object is to provide an angularly adjustable grinding headhaving, in projecting relation therefrom, interchangeable belt-backingmembers.

In the drawings:

Fig. l is a side elevational view of a belt-grinding machine embodyingthe invention;

Fig. 2 is a top plan view of the machine;

Fig. 3 is a vertical sectional view taken on line 3-3 of Fig. 1;

Fig. 4 is an enlarged sectional view taken on line 4-4 of Fig. 3; i

Fig. 5 is a sectional view taken on line55 of Fig. 3;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 1;

Fig. 7 is an elevational rear view of one of the projecting belt-backingmembers;

Fig. 8 is a side elevational view; partially in section, illustratingthe belt-backing member of Fig. 7;

Fig. 9 is a view similar to Fig. 8, but illustrating a beltbackingmember of somewhat different form and dimensions than that shown in Fig.8, and interchangeable with the latter; v

Fig. 10 is a fragmentary view similar to. Fig. 7, but illustrating thebacking member of Fig. 9;

Fig. 11 is a diagrammatic view on a smaller scale illustrating thebelt-grinding machine grinding an external surface of an article; and

Fig. 12 is a diagrammatic view on a still smaller scale illustrating thebelt-grinding machine grinding the internal surface of an article. a

In the drawings, the reference numeral 10 indicates the support or tableof the machine. In the illustrated form this table is of oblong form andis provided at one end portion with an upright standard 11 fixedthereto. At the otherend portion thereof the table 10 is provided with afixed upstanding block 12. A removable worksupporting member 13 has adepending block 14 fixed thereto and slidable on the block 12 lengthwiseof the table. The block 14 may have a rearwardly projecting part 15provided at its rear extremity with a pointer 16 and having at the rearportion thereof a dependingele ment in fixed relation thereto andsupporting a screw 17 in axially fixed relation thereto. The screw 17 isarranged lengthwiseof the table and has at the rear of the dependingelement 20 a hand wheel 21 fixed thereto. The forward end portion of thescrew 17 is threaded in a bore 22 provided in the block 12. It will bemanifest from the foregoing that the operation of the hand wheel 21effects nited States Patent 0 adjustment of the work-supporting member13 lengthwise of the table. The hand wheel 21 may be provided withcircumferential calibrations 21 (see Fig. 2) cooperating with thepointer 16 to indicate the degree of movement of the work-supportingmember as it is shifted longitudinally of the table by operation of thehand wheel. A conventional manually operated clamping member, indicatedgenerally at 23, is arranged transversely of the table 10 and extendsthrough the blocks 12 and 14 to clamp the blocks to one another so thatthe work-supporting member 13 may be held in adjusted position during agrinding operation.

The upright standard 11 fixed to the table 10 extends into a verticallyarranged tubular part 24 which is movable up and down on the standard11. The tubular part 24 has a fixed closure element 25 at its upper endand a hand wheel 26 is journaled in the element 25 in axially fixedrelation thereto. The hand wheel 26 is fixed to one end of a screw 27which extends downwardly in a bore 28 in the standard 11 and having athreaded portion 28 The arrangement is such that operation of the handwheel 26 effects vertical adjustment of the tubular part 24. At theupper end portion thereof the tubular part 24 carties in fixed relationa horizontal projecting arm 29 which, at its distal end, has an offsetportion 30 which is thickened and which may have the form best shown inFigs. 2 and 3. The thickened portion 30 of the arm may be recessed, asat 30*, to reduce the weight of the arm. The arm 29 extends rearwardlyfrom the tubular part 24 and lengthwise of the table 10. Adjacent oneside thereof the thickened and offset portion 30 of the arm is providedwith a longitudinal bore extending therethrough to receive, in slidablebut non-rotatable relation, a motor support 31 of elongate form. A screw32 is threaded in the threaded portion 33 of a bore 33 in the support 31to effect adjustment of the motor support 31 lengthwise of the arm 29and the table 10, the screw being supported in axially fixed relation bya part of the arm portion 30 and being provided with a hand wheel 34 toeffect rotary movement of the screw. An electric motor 35 is supportedby the support 31 in a manner whichwill appear hereinafter. The motor 35has an output shaft 36 which extends through a horizontally elongatedslot 37 in the arm 29, the output shaft 36 having a pulley 38 thereon todrive and endless grinding belt 39. It will be understood from theforegoing that the slot 37 in the arm provides clearance for the outputshaft 36 of the motor when the motor is adjusted lengthwise of the arm.

The motor 35 has a fixed attaching plate 40 clamped to a plate 41 byscrews 42 which extend through corner flanges 43 overlying portions ofthe plate 40 and fixed to the plate 41, as shown in Figs. 1 and 2. Asshown in Fig. l, the plates 40 and 41 are arranged vertically. Ahorizontally disposed plate 44 extends between the upper pair of cornerflanges 43 and receives trunnion members 45 (see Fig. 2) pivoting theplate 41 for vertical swinging movement on the plate 44. The plate 44 issupported on the upper edge of a plate 46 arranged vertically in spacedrelation to the plate 41. The plate 44 is pivoted to the upper edge ofthe plate 46, as at 47, the pivot (see Fig.2) being disposed adjacentone side edge of the plate 46- and the arrangement being such that theplate 44 may swing horizontally on the plate 46. The central portion ofthe plate 46 is fixed by any suitable means to the forward end of themotor support 31. To adjust the plate 44 angularly with respect to theplate 46, the plate 44 is provided with a flange 48 carrying, in axiallyfixed relation thereof, an adjusting screw 49 threaded into the plate 46adjacent the side thereof remote from the pivot 47.

To control the swinging movement of the plate 41 on the plate 44 the arm29 carries a conventional pressure device, indicated generally at 50,and of the adjustable type, having a plunger 51 bearing against a lowerportion of the plate 41 to urge the latter in a generally forwarddirection. It will be apparent from the foregoing that the pivotallymounted plate 41, swingable on the trunnion members 45 and under thecontrol of the pressure device 50, mounts the motor 35 in the mannertending to lessen or absorb shock or strain imposed on the belt 39. Thepivotal plate 44, mounted on the plate 46 and controlled by theadjusting screw 49, permits movement of the motor to adjust the angularposition of its driving pulley 38 in accordance with the run of the belt39.

The grindingbelt 39 is directed over an idler pulley 52 provided on anangularly adjustable grinding head, indicated generally at 53, mountedon the portion 30 of the arm 29. An idler pulley 54 is provided on thehead 53. While, in the operation of the machine, the belt always passesover the pulley 52, the belt may or may not be trained over the pulley54, depending upon the nature of the grinding operation, as will appearhereinafter. The head 53 is provided with an elongated, projectingbeltbacking member, indicated generally at 55, having one end removablysecured to the head and having a roller 55* at the other end thereof.The grinding belt 39 rides over the length of the backing member 55 andis trained over the roller 55*. The pulleys 38, 52 and 54, as well asthe roller 55*, may be crowned to facilitate the centering of the belton the pulleys and the roller. As shown in Fig. 1, the belt passes fromthe driving pulley 38 to the idler pulley 52 and then over the roller 55The belt may return directly to the driving pulley from the roller 55or, if the grinding operation requires it, the belt may pass over theidler pulley 54 (as shown in broken lines in Fig. 1) before returning tothe driving pulley. To slacken the belt 39 sufficiently to train it overthe pulley 54 the motor carrying the driving pulley must be shiftedrearwardly or outwardly on the arm 29 by operation of the hand wheel 34.

Turning to the details of the grinding head 53 and the parts associatedtherewith, it will be seen that, as shown in Fig. 5, the grinding headmay be of rectangular outline. The head may take the form of a ratherthin block and may be mounted on the thickened portion 30 of the arm bya shaft 56 extending transversely through the last-mentioned portion ofthe arm and revoluble therein. The shaft 56 is inserted in the arm 29from the right side of the latter, as viewed in Fig. 3, and has a fixedcollar 57 which may abut the last-mentioned side of the arm when thehead 53 is clamped to the arm. The left end of the shaft as viewed inFigs. 3 and 6 may be threaded, as at 58, and received in acorrespondingly threaded bushing 59 fixed in the grinding head. Theshaft 56 at the side of the arm at which the collar 57 is disposed, hasfixed thereto a crank arm 60 for manipulation by the operator of themachine. The arrangement of the shaft 56 is such that it normallyservesto clamp the angularly adjustable head 53 against thecorresponding side of the arm 29. However, when the crank arm 60 isrotated by the operator in a direction to tend to unt'hread the shaft 56from the head-53, the clamping pressure of the shaft 56 is removed andthe head 53 may be angularly adjusted with respect to the arm 29 and theshaft 56 on which the head is pivoted. The manner of effecting angularadjustment of the head 53 will appear hereinafter.

The inner face of the block forming the head 53 may be recessed, as at61 and 62, to reduce the weight of the head. The inner face of the headis also provided with upwardly spaced grooves 63 and 64 arranged inparallel relation to one another and extending generally lengthwise ofthe arm 29. The rear end of the groove 64 terminates in a recess 64* inthe rear edge of the head 53, while the rear end of the groove 63terminates in a recess 63 formed in the rear edge of the head. The

recess 64- provides a rearwardly facing shoulder 64 on the head and therecess 63 provides a rearwardly facing shoulder 63 on the head. Thegroove 64 in the head receives a correspondingly shaped slide 65 flushwith the inner face of the head while the groove 63 receives a similarslide 66, the slides being arranged for lengthwise movement in theirrespective grooves. The rear end of the slide 66 carries, at rightangles and in fixed relation thereto, an arbor 66 for the idler pulley54. The slide 65 carries, in like manner, an arbor 65 for the idlerpulley 52. The arbors 65 and 66 extend through the recesses 64* and 63respectively. The shoulder 69 provides an abutment for the arbor 65 tolimit forward adjustment of the idler 52 carried by the slide 65. Theshoulder 63 serves as an abutment for the arbor 66 to limit forwardadjustment of the idler pulley 54- carried by the slide 66. As shown inFig. 5, a clamping screw 68 extends downwardly in the head 53 from thetop thereof to clamp the slide 65 in adjusted position. As shown in thelast-mentioned view, a longer clamping screw 69 is similarly arranged inthe head 53 to clamp the slide 66 in adjusted position.

To adjust the head 53 angularly with respect to the arm 29 and thework-supporting member 13 once the head has been unclamped from the arm29 by operation of the crank arm 60, the head is provided with a stubshaft 79 fixed thereto and extending into a' recess 71 in the thickenedportion 3-6 of the arm. As best shown in Fig. 4, the recess 71 iselongated lengthwise of the arm 29 and provides vertical clearance forthe shaft 70 so that the head 53 may be .angularly adjusted withinlimits. A compression spring 72 carrying a follower '73 is interposedbetween the. forward endof the elongated recess 71 and the stub shaft 76to urge the shaft generally rearwardly so that the head 53 is angularlybiased. The follower 73 of the spring may bear against a flat 76* pro- 4vided on the shaft 70 best shown in Fig. 5. An adjus-tin screw '75 ('seeFig. 4) is threaded forwardly through the rear or distal end of the aim29 to bear against the stub shaft 76. By turning the adjusting'screw '75in a direction to feed 'it forwardly, the stub shaft '70, against thepres sure of the spring 72, may be moved generaliy forwardly to effectmovement of the head 53 in a counterclockwise direction as viewed inFig. 1. When the adjusting screw 75 is turned in the other direction,that is, in a direction to retract it, the stub shaft 71 under theinfluence of the spring 72, follows the screw 75 and clockwise movementof the head 53 is effected. Thus it will be understood that the spring72 and the follower 73, together with the adjusting screw 75, jointlycontrol the angular adjustment of the head 53 through the stub shaft 7it.

To facilitate the adjustment of the grinding head to the proper angularposition before the commencement of a grinding operation, a gauge,indicated generally at 7 is provided to give the machine operator avisual indication of the extent, as in degrees, to which the grindinghead is tipped. The gauge 76, which may be of conventional construction,has a dial 78 provided with suitable indicia circumferentially thereof,and the gauge has a pointer 79 for cooperation with the dial andactuated by the usual plunger or feeler 80. As best shown in Fig. 4, thegauge 76 is mounted on the upper surface of the arm 29 and the feeler 80of the gauge extends downwardly into the arm and into therecess 71provided in the arm, the lower end of the feeler being engageable withthe stub shaft 70. The feeler 80 of the gauge rides on the curvedsurface of the stub shaft 70 and the arrangement is such that when theshaft 70 is rotated on the axis of the shaft 56, the shaft 70 effectsvertical movement of the feeler 80. The vertical position of feeler 80is indicated by the position of the pointer 79 on the dial 78. After thegrinding head 53 is adjusted to the desired position by operation of theadjusting screw 75, the head may be clamped in adjusted position byoperation of the crank arm 60.

aasasea The belt-backing member 55 which, when assembled with thegrindingrhead- 53 projects downwardly from the latter, is best shown inFigs. 7 and 8. The member 55 includes a bar 82 of rectangular crosssection having one end thereof removably secured to an attaching plate83 by a manually operable screw 84. The attaching plate 83 has a flange85 to abut an edge portion of the bar 82 and prevent angular movement ofthe bar 82 relatively to the plate 83. As shown in Fig. 7, the attachingplate 83 is notched, as at 86. A manually operable screw extends intothe notch 86 and is threaded into the rear edge portion of the head 53to removably clamp, the attaching plate 83 to the rear edge of the head53, as shown in Fig. 5. On the forward face and adjacent the lowerextremity thereof, the bar 82 is provided with a forwardly projectingblock 87 and is recessed, as at 88. A bifurcated holder 89 is providedto hold the roller 55 on the bar 82, the arms of the holder 89 beingdisposed at opposite sides of the block 87, as shown in Fig. 7. Theholder 89 extends into the recess 88 in the bar 82. The holder 89 issupported on the bar 82 by a bolt 91 having a threaded portion receivedin a correspondingly threaded bushing 92 fixed in the bar 82. The bolt91 has a shank .portion extending through a bore 93 provided in theholder 89, the last-mentioned shank portion having clearance with thebore 93. The bolt 91 has a tapered head portion 94 received in acorrespondingly formed seat provided in the holder 89. The arrangementof the bolt 91. in the holder 89 permits the holder 89 to be tippedslightly forwardly at its lower end when the bolt 91 is not threadedinto the bushing 92 as far as it will go, to hold the holder in flatwiseengagement with the bar 82, as shown in Fig. 8, but is loosenedsuificiently to permit this forward tipping movement, which may bedeemed necessary to adjust the roller 55 generally forwardly orrearwardly. To maintain the holder 89 in a tipped position, a screw 95is provided to .extend through. the holder 89 in threaded relationthereto .so as to bear against the forward face of the bar 82.

The holder 89 is provided with depending ears or lugs 96 which supportthe roller 55* from its respective ends, adjacent but slightly spacedfrom the lower extremity of the bar 82. To mount the roller 55 on thelugs 96, the lugs are provided with trunnion members 97, and thetrunnion members, in turn, support suitable antifriction members 98extending into the respective ends of the roller 55 in supportingrelation to the latter. To provide as much support as possible for thebelt throughout the length of the belt-backing member 55, the rear faceof the bar 82 approaches the periphery of the roller 55 This is achievedby curving the lower extremity of the bar 82, as at 100. A portion ofthe holder 89 is provided with a corresponding curvature, as at 101. Toenable the roller holder 89 to be angularly'adjusted on the axis of thebolt 91, after the bolt 91 has first been loosened, the arms of theholder 89 are provided with two adjusting screws 182 which bear againstopposite sides of the block 87 on the bar 82.

The belt-backing member 103, shown in Figs. 9 and 10, and which issimilar to the belt-backing member 55 and interchangeable with thelatter, is of somewhat different form and of smaller dimensions. Anarrower grinding belt may be used on the machine when the beltbackingmember 103 is employed, and it will be understood that the member 103 isemployed on the grinding machine when it is desired to grind or polishsmaller surfaces than the surfaces ground by the machine when thebacking member 55 is employed thereon. In the form of the backing membershown in Figs. 9 and 10, the roller 104, similar to the roller 55, maybe of truly cylindrical form, if desired.

The operation of the belt-grinding machine will be manifest in view ofthe foregoing description of its construction, To set up the machine fora particular grind- 6. ing operation, it is first-necessary to choose ordecide upon a belt of the proper abrasive quality and of the properwidth. A belt-backing member must be chosen in accordance with therequirements of the particular job and the width of the belt. Thebelt-backing member is then attached to the head 53. If an internalsurface is to be ground, the idler or guide pulleys 52 and 54 must beadjusted generally lengthwise of the arm 29 so .that the belt may runsmoothly and closely over the rear face of the belt-backing member andrather closely over the roller holder 89 on the forward face of thebeltbacking member. The motor-driven pulley 38 may be adjustedlengthwise of the arm 29 by operation of the hand, wheel 34 so that thebelt may be slipped over the last-mentioned pulley and then given theproper tension. The grinding head 53, with the belt-backing memberattached to it, may then be angularly adjusted to meet the requirementsof the particular grinding operation. The driving pulley 38 may also beangularly adjusted in accordance with the run of the belt. The arm 29carrying the grinding head 53 may be raised or lowered by operation ofthe hand wheel 26 and the work previously clamped (not shown) to thework-supporting member 13 may be advanced toward or retracted from thebeltbacking member by operation of the hand' wheel 21. The motor 35 maythen be started to commence the grinding of an internal surface, such anoperation being shown diagrammatcally in Fig. 12.

When an external surface of an article is to be ground, the belt isremoved from the idler or guide pulley 54 to reduce flexing of the belt.The belt passes directly from the belt-backing member to the drivingpulley 38. To remove the belt from the pulley 54, the belt may first beslackened by operation of the hand wheel 34. After the belt has beenremoved from the pulley 54, it may be tensioned by again working thehand wheel 34. To grind an external surface of an article the arm 29 maybe low- .ered to an extent that the belt-backing member extends through.the work-supporting member 13. To provide clearance for thebelt-backing member and the belt, the work-supporting member 13 isslotted, as at 13. Such a grinding operation is shown diagrammaticallyin Fig. 11.

In view of the foregoing disclosure, it will be evident that there isprovided an improved belt-grinding machine which may be employed forgrinding both external and internal surfaces of articles. One advantageof the beltgrinding machine is its great fiexibilty of operation. Afurther advantage of the machine is that it includes an angularlyadjustable grinding head and improved means for gauging the degree ofadjustment of the head. Still another feature of the machine resides inthe provision of an angularly adjustable grinding head having, inprojecting relation therefrom, improved and interchangeable belt-hackingmembers.

It will be apparent to those versed in the art that the grinding machineillustrated in the drawings and described above is susceptible ofvarious modifications and changes in details without departing from theprinciples of the invention and the scope of the appended claims.

What I claim is:

1. A belt-grinding machine comprising a support having front and rearends, a standard rising from the support at the front end, ahorizontally and rearwardly extending arm adjustable up and down on thestandard, a grinding head pivotally mounted on one side of the rearportion of the arm for angular adjustment in a vertical plane, meanscarried by the arm and cooperating with the head for effecting angularadjustment of the latter, a motor-driven pulley, means mounting themotordriven pulley on the arm forwardly of the head, said means mountingthe pulley tor rectilinear adjustment along a portion of the arm andalso mounting the pulley for angular movement in two planes at rightangles to each other, an endless abrasive belt trained over the pulleyto be driven by the latter, a belt-backing member on the grinding head,and a pair of guiding rollers mounted on the head to guide the beltrelatively to the belt-backing member, the driving pulley beingshit-table rectilinearly so that the belt may be disengaged from one ofsaid guide pulleys and run free from the latter.

2. A belt-grinding machine as defined in claim 1, wherein thebelt-backing member is of elongate form and projects generallydownwardly from the grinding head.

3. A belt-grinding machine as defined in claim 1, wherein aWork-supporting member is mounted on said support below the grindingvhead, the work-supporting member being mounted on said said support foradjustment toward and away from the front end of the latter, and thework-supporting member having an opening therein providing clearance forthe belt-backing member and the belt. I

4. In .a bah-grinding machine, a driving pulley, an endless abrasivebelt trained over the pulley to be driven by the latter, a support, acantilever member mounted on the support, a grinding head pivotallymounted on the distal end portion of the member for vertical swingingmovement, the grinding head having a pulley carried thereby and overwhich the belt is trained, means carried by said portion of the memberand cooperating with the head to effect angular adjustment of the latteron its pivotal axis, and gauge means mounted on said portion of themember and cooperating with the first-named means to provide a visualindication of the degree of angular adjustment of the head.

5. In a belt-grinding machine, :a support, a driving pulley, an endlessabrasive belt trained over the pulley to be driven by the latter, agrinding head mounted on the support for angular adjustment with respectto the latter,

a belt-backing member of elongate form having one end thereof removablymounted on the grinding head and having the other end projectingoutwardly from the head and having at the last-mentioned end a holderfor a roller over which the belt may be trained, the holder beingmounted on the member for angular adjustment in two planes which are atright angles to each other, a guide pulley :adjustably mounted on thehead for guiding the belt relatively to one side of the belt-backingmember, a second guide pulley adjustably mounted on the head for guidingthe belt-relatively to the remote side of the belt-backing member, andthe driving pulley being adjustably mounted on the support so that thebelt may be slackened and tensioned to enable the belt to be disengagedtrom one of the guide pulleys and run free from the latter.

6. In a belt-grinding machine, a drive pulley, an endless abrasive belttrained over the pulley to be driven by the latter, a support, acantilever member mounted on the support, a grinding head pivotallymounted on the distal end portion of the member for vertical swingingmovement, a belt-backing member of elongate form projecting from thehead in fixed relation thereto and over which the belt is trained, guidemeans on the head for guiding the belt relatively to the belt-backingmember, means carried by said portion of the cantilever member andcooperating with the head to effect angular adjustment of the latter onits pivotal axis, and gauge means mounted on said portion of thecantilever member and cooperating with the first-named means to providea visual indication of the degree of angular adjustment of the head.

7. In a belt-grinding machine, a drive pulley, an endless abrasive belttrained over the pulley to be driven by the latter, a support, acantilever member mounted on the support, a grinding head pivotallymounted on the distal end portion of the member, the grinding headhaving a pulley carried thereby and over which the belt is trained, thehead also having a fixed stub shaft in eccentric and parallel relationto the pivotal axis of the head, the stub shaft extending with clearanceinto a recess formed in said portion of the member, a spring disposed insaid recess and urging the head in one rotary direction through pressureon the stub shaft, a screw carried by said portion of the member andbearing against the stub shaft to move the head in the other rotarydirection, and means mounted on said portion of the member andcooperating with the head to provide a visual indication of the degreeof angular adjustment of the latter.

8. A belt-grinding machine as defined in claim 7', wherein the means forindicating the angular adjustment of the head comprises a gauge carriedby said portion of the member and having a movable part riding on thestub shaft.

9. A belt-grinding machine as defined in claim 8, wherein the grindinghead is pivoted to the cantilever member by an axially adjustable shaftextending into the member and the head, the shaft being rotatablerelatively to the member and to the head and having means thereon toclamp the head to the member when the head is in angular adjustedposition.

References Cited in the file of this patent UNITED STATES PATENTS1,019,066 Mary et al. Mar. 5, 1912 1,257,691 Fraser 'Feb. 26, 19181,820,377 Curtis Aug. 25, 1931 1,974,806 Curtis et al Sept. 25, 19342,061,607 Andrie Nov. 24, 1936 2,463,287 Krueger Mar. 1, 1949 2,470,615Grover May 17, 1949 2,573,220 Riedesel et a1 Oct. 30, 1951 FOREIGNPATENTS 85,425 Czechoslovakia Dec. 1, 1955

